that will continue to settle. engineers tell us buildings with shallow foundations continue to sag and sink. while most high rises have finished settling or have less than a foot to go. the lack of solid ground under many san francisco buildings is of course not a new problem. as tara reported it was clear after the 1906 quake that some buildings were not just on shaky ground but on sinking ground. in 1995, diane wire reported on a new map that showed which areas were the most in danger. >> reporter: there's nothing quite like a beautiful sunny day in san francisco. these are views famous around the world. but today, geologists introduced us to a new color code of san francisco. the red represents the bay mud or landfill areas which are the least stable and therefor the most dangerous. the yellow represent sand, the green sheet rock and the blue represents bedrock the most stable. just to give you an idea of this map. this two story home is built on bedrock. directly across the street, the high rise apartment building is built on sand. much of the finings are expected. russian hill is bedrock. but
